Occult macular dystrophy (OMD), also known as Miyake disease, is a rare, autosomal dominant disease. Symptom onset is variable; the majority of patients present in their late twenties with a progressive bilateral decline of central vision, photophobia, and central scotoma. The mean visual acuity is 20/80 but can vary from 20/30 to 20/200 or worse. No significant abnormality is seen in the fundus or fluorescein angiography. Optical coherence tomography (OCT) findings range from blurring of the interdigitation zone (IZ) and the ellipsoid zone (EZ) with thinning of the outer nuclear layer to extinguished IZ and disrupted EZ resulting in the optical gap in the fovea (Fig. 19.1). Full-field electroretinography (ERG) is normal; multifocal ERG and pattern ERG reveal diminished amplitudes, suggestive of macular dysfunction.